Buffers (also at times called accumulators) have been utilized between an upstream delivery station and a downstream receiving station to buffer flows by accumulating articles when the capacity of the downstream receiving station is either shut down or run at a speed wherein it cannot handle the number of articles being fed by the upstream delivery station. Various types of accumulators have been proposed. Some provide first-in, first-out (FIFO) accumulation so that certain articles do not dwell long in the accumulator system.
Some accumulators are horizontal, such as Models 6200 or 7100 DYNAC® sold by Hartness International, Inc. In these accumulators, articles travel from a conveyor stream horizontally and linearly on one belt in a first direction and then reverse direction and flow horizontally and linearly on another belt in an opposite direction to rejoin the conveyor stream. Other accumulators are helical, such as the Models 6400 or 6600 DYNAC® also sold by Hartness International, Inc. In these devices, the first and second conveyors travel parallel curved paths upward and downward. Use of such helical accumulators allows for greater length of conveyor chain for accumulation in a given amount of floor space because some of the accumulation is overlappingly vertical. Accordingly, more articles can be accumulated in a given amount of floor space using a helical accumulator than using a horizontal accumulator with the same width chain.
Other conveyors have been proposed with multiple parallel conveyor lanes used for accumulation. Some of such accumulators use horizontal, linear lanes, such as those disclosed in WO 2012/078661 A1 (Steeber). These devices require a great deal of complexity to drive each lane independently. Backups before and after each lane can happen. Steeber attempts to address these backup issues with extremely complex solutions, including adding additional accumulators directly upstream and downstream of the lanes.
U.S. Pat. No. 7,775,344 B1 (Balk) discloses accumulators with multiple lanes that are arranged in various spiral configurations. The Balk devices would likely also be subject to upstream and downstream backups during operation. Also, some customers do not wish to have accumulation lanes extend vertically as far as these devices do.
Accordingly, further improvements providing reliable and cost effective high-density buffering/accumulation would be welcome, including designs that address one or more of the drawbacks of the above multi-laned devices or designs that provide other benefits.